I’m working on a project using a PLC controller that is monitoring a process. I have a HTML page now that refreshes itself and shows values of registers.

I am using: <iframe src=”readreg.htm;reg-R1;fmt-INT;rfs-5″>
</iframe>
The code above reads the value of register R1 from controller’s inner page readreg.htm, which I can’t see and enter (it’s hide somewhere). Iframe returns a value(number) but of course in frame. Iframe works fine.

I want to get the value from iframe (number from register) and put it into variable so I can create a chart.

I can’t use php, only javascript.
I’ve tried to do it for weeks but every solution doesn’t work. Hope you can help me.

Unless we look into your code, we can’t predict what to suggest for your project. Can you kindly create a sample project and share your code, so that we can look into it and help you out. Also this relevant topic from stack-overflow might help you.